Typically, modern wind turbines are connected to an electric utility grid in order to be able to generate and supply electricity to consumers located remotely from the wind turbines.
The rotor speed of the wind turbine increases and decreases with changing wind speed in order to subtract as much energy from the wind as possible, and consequently the electric generator generates electricity with a variable frequency. The electricity is converted by a frequency converter to electricity with a fixed frequency which is supplied to the electric utility grid.
The frequency converter may introduce different stray currents to the electric generator such as in the shaft and housing of the generator. In order to avoid the stray current it is well known to ground the stationary and rotating parts of the generator.
However, the well known ways of grounding the stationary and rotating parts may often create problems in relation to circling stray currents within the generator. Circling stray currents may result in bearing corrosion which negatively affects the service life of the generator.
It is therefore an object of the present invention to provide a solution which is more efficiently adapted to the situation of an electric generator such as in a wind turbine.